The invention relates to a vocal valve to be applied to a tracheostoma.
A tracheostoma is opened in case a patient has difficulties to breath in a natural way, e.g. due to formation of phlegm, or in case the patient has been laryngeectomized involving excision of the larynx and the vocal cords no connection existing between trachea and the mouth. In the latter case a voice prosthesis often is placed by surgery in a fistula in the wall between trachea and esophagus in order that the patient notwithstanding the lack of vocal cords shall be able to produce speech, which is done by pressing air through the voice prosthesis to esophagus where speech is produced by the mucous membranes being put into vibration. In order that this can take place it is necessary to close the tracheostoma when speech is to be produced, and this is done either by the patient covering the tracheostoma with the fingers or by closing manually a valve located in the tracheostoma. It is necessary to close the tracheostoma also in case the vocal cords are still there because the air otherwise will escape through the tracheostoma instead of escaping via the vocal cords and the mouth in the usual way, but in the latter case the valve can comprise a check valve which opens at inspiration and closes at expiration because the expiration can take place in the normal manner via the vocal cords and the mouth.
For laryngeectomized patients automatic vocal valves have been proposed (U.S. Pat. Nos. 4,582,058 and 4,325,366) which are kept opened during normal breathing but close by a pressure shock being produced in trachea when the patient wishes to produce speech. Valves of this type do not function sufficiently well on patients with a tracheal cannula and therefore are taped directly against the skin of the patient""s neck.
On laryngeectomized patients who inspirate and expirate through the tracheostoma, a regenerative moisture and heat exchanger, a so-called xe2x80x9cartificial nosexe2x80x9d, is connected with the tracheostoma. It is formed as a filter which absorbs moisture and heat from the expiration air said moisture and heat hen being given off to the inspiration air (SE-B-348 643 and SE-B-467 195). It has also been proposed according to WO-A-95/17138 to combine such a filter with a valve which can be operated manually in order to close the tracheostoma.
Tracheotomized patients often have some type of cannula, i.e. a curved tube which is passed through the tracheostoma into trachea and the purpose of which is to keep the tracheostoma open and to form a holder for a vocal valve and/or a moisture and heat exchanger which, however, instead can be taped directly against the skin on the patient""s neck.
The vocal valve according to the invention is of the kind disclosed in WO-A-95/17138 and comprises a filter for moisture and heat exchange at breathing through the vocal valve, a housing receiving the filter and having a first opening at one side of the filter to be connected to the tracheostoma, at least one second opening at the opposite side of the filter, communicating with the surroundings, and a manually operated valve element for blocking the air passage through the filter.
In the vocal valve according to WO-A-95/17138 the airflow through the tracheostoma via the filter is blocked by closing said second opening at manual operation of the valve element. This involves a clear drawback because only a limited area can be provided in a plane of the opening and thus of the filter in order to effect a sealed closing; otherwise the vocal valve at the necessary filter volume will be unreasonably high. A small area of the filter implies bad moisture and heat exchange.
The purpose of the invention is to overcome this drawback which is achieved by a vocal valve for connection to a tracheostoma, comprising a regenerating filter for moisture and heat exchange at breathing through the vocal valve, a housing receiving the filter and having a first opening at one side of the filter to be connected to the tracheostoma, at least one second opening at the opposite side of the filter, communicating with the surroundings, and a manually operated valve element for blocking the air passage through the filter, characterized that a socket projecting into the interior of the housing forms a valve seat defining said first opening, to be sealaingly engaged by the valve element at manual operation thereof. Thereby, great freedom is achieved with regard to the construction of the filter which can be dimensioned for optimal moisture and heat exchange function, the valve element at the same time having to close a small area only, which requires a very small force at operation of the valve element. If on the contrary the valve element shall close an optimal filter area in the vocal valve according to WO-A-95/17138 a considerably greater force is required, which causes inconvenience for the patient particularly if the vocal valve is provided with a cannula because this passes into a very delicate area of the patient. Above all patients which have recently had surgery are very susceptible.